Loss of vigour in leek (Allium porrum L.) seed lots is accompanied by the appearance of damage to ribosomal RNA in quiescent embryo tissue. Polyethylene glycol osmopriming treatments of such low-vigour seed permit replacement of this damaged ribosomal rRNA over a 7-day priming period. Low-vigour leek seeds germinated for 6 days without a prior osmopriming treatment still exhibit evidence of damaged ribosomal RNA in embryo tissue. Osmoprimed leek seeds dried back whilst still in the desiccation-tolerant state retain most of the benefits conferred by priming treatments. Osmoprimed leek seeds dried back when having reached the desiccation-sensitive state germinate poorly, if at all, and exhibit much reduced rates of protein synthesis in embryo tissue upon rehydration compared to desiccation-tolerant seeds. Embryo tissue from dried back, desiccation-tolerant seeds exhibits the capacity for much higher levels of protein synthesis than embryo tissue from unprimed seeds at equivalent stages of imbibition. RNA levels continue to increase in embryo tissue upon rehydration of dried back, desiccation-tolerant leek seeds but not in desiccation-sensitive seeds. Loss of protein synthetic capacity in desiccation-sensitive seeds during rehydration is accompanied by increasing levels of ribosomal RNA degradation. Such ribosomal RNA degradation may be indicative of the germinative capacity of leek seeds dried back after osmopriming treatments.

An osmotic priming treatment of 14 days in a −1.0 MPa polyethylene glycol solution improves the germination performance of a highvigour seed lot of leek (Allium porrum L., cv. Verina). Using in vivo pulse-labelling, two-dimensional polyacrylamide gel electrophoresis and fluorography, five polypeptides were found to be synthesized in embryonic tissue at 14 days of priming that were not present at 4 days of germination without prior priming. These polypeptides were still synthesized at 6 h of germination following priming. This time point lies in the 6–12 h lag phase in protein synthesis previously observed in leek embryo tissue during germination of primed seeds where there is little increase in the rate of synthesis over that seen at the end of priming. None of the polypeptides was synthesized at 2 days of germination after priming, a period of seedling growth. The five polypeptides appear to be specifically associated with the priming period. Two additional polypeptides were found in leek embryos that were synthesized at higher levels at the end of priming than during germination alone. These continued to be synthesized, at lower levels in leek embryo tissue upon germination after priming. Several polypeptides were identified in leek endosperm tissue which were synthesized at higher levels during priming than during germination and also two polypeptides whose synthesis appeared to be specific to germination.